The present invention relates to a method of testing characteristics of a battery, and more particularly to a comparative method of testing individually the characteristics of a plurality of batteries making up a battery set.
An uninterrupted supply of direct current is an absolute necessity for keeping a normal operation of a computer system or a communication system. However, an incident of power interruption can take place at any moment, due to a simple power stoppage or a malfunction of a rectifier. In order to safeguard the normal operation of the computer system or the communication system, a standby battery set is generally provided to be put into service on an emergency basis. Such standby battery set is always kept ready to serve by being connected with a floating charge of the rectifying system.
Before the battery set is ready to be put into service, it has to be initially charged and then recharged only after it has been discharged successfully on a trial basis. However, the capacitance of the battery set can be eventually eroded after a certain period of time. Such erosion of capacitance may be caused by an incident such as a detachment of active substances, or a hardening of polarized plates; nevertheless the erosion of the battery capacitance can happen to only one of batteries making up the entire battery set which works in tandem. If such incident as described above takes place, the defective battery, which has an inadequate capacitance and an excessive internal resistance, may be responsible for a reversal of electrical charge at such time when the battery set is in the midst of discharging, thereby bringing about an overload of the battery set. It is therefore necessary to detect the defective battery of the entire battery set, so as to ensure that the normal operation of the computer system or the communication system is not unduly jeopardized by the defect of the standby battery set at such time when an interruption of city power service takes place.
According to the prior art method of testing the capacitance of batteries of the standby battery set, it is necessary that the computer system or the communication system is first disconnected with the standby battery set, which is then caused to carry a false load, such as a resistance, for a discharging test. The electrical current and the time of the discharging test of the battery set are dependent on the capacitance of the batteries in terms of ampere-hour. As a result, it often takes several hours of discharging and more than ten hours of charging before one can figure out the capacitance of the battery set in one testing of the battery set, assuming that the capacitance of the battery set is 3200 ampere hours and that discharging current is selected at 400 amperes, with the discharging time being eight hours. In addition, it is required in the course of carrying out such testing that there is always some one who is present at the testing site to record the voltage of each of batteries of the set, and the specific gravity and the temperature of the electrolyte. In other words, such prior art method of testing the battery set results in a senseless waste of the man power. For example, a local area communication system is generally backed up by a standby battery set which is composed of at least 24 batteries. It is conceivable that the task of checking and testing the characteristics of each of the twenty four batteries is extremely cumbersome and costly.